Metal roof

ABSTRACT

A standing seam roof comprising seamed-edge panels held down on the roof supporting structure by clips which have V-shaped sections interfitting with V-shaped sections on the panels. The clips are concealed in the seam.

United States Patent 1 Day et al.

1 1 June 17, 1975 METAL ROOF [75] Inventors: Donald L. Day, Guysville,Ohio;

Charles H. l-lalstead, Poca, W. Va.; Neil F. Huck, Lowell, Ohio [73]Assignee: Textron lnc., Providence, RI.

[221 Filed: July 17, 1974 [21] Appl. No.: 489,135

Related U.S. Application Data [62] Division of Ser, No. 313,754, Dec 11,1972,

[52] U.S. C1. 52/520; 52/489; 52/528; 52/542 [51] Int. Cl. E04D 1/00[58] Field of Search 52/518, 519, 520, 528, 52/539, 542, 545, 492,593,478, 483, 588

[56] References Cited UNlTED STATES PATENTS 483,966 10/1892 Montross52/520 2,100,957 11/1937 Hoffman 52/588 TOPSIDE WALL, 16

UNDERSlDE WALL 17 2,142,305 1/1939 Davis 52/593 2,739,677 3/1956Greulich 52/518 3,055,461 9/1962 De Ridder 52/518 3,062,337 11/1962Zittle 52/404 3,234,697 2/1966 Toti 52/588 3,462,906 8/1969 Schroyermn521478 3,511,011 5/1970 Straus 52/545 3,708,943 1/1973 Thomas 52/588FOREIGN PATENTS OR APPLICATIONS 1,507,634 11/1967 52/588 PrimaryExaminer-John E. Murtagh Attorney, Agent, or F {rm-Frederick .1. Olsson[57] ABSTRACT A standing seam roof comprising seamed-edge panels helddown on the roof supporting structure by clips which have V-shapedsections interfitting with V- shaped sections on the panels. The clipsare concealed in the seam.

10 Claims, 11 Drawing Figures r 9 Op PATENTEDJUH 17 I975 m i A w m;

SHEET PATENTEDJUN 1 7 I975 2 3; mew? METAL ROOF This application is adivision of our copending application Ser. No. 3l3,754 filed Dec. 11,1972 and entitled METAL ROOF.

This invention relates to pre-engineered metal buildings and inparticular relates to an improved roof structure for such buildings.

The invention contemplates improvements in standing-seam type metalroofs, the adjacent panels ofwhich have inter-fitting seamed edgesengaged with concealed clips which hold the panels down on the structurefor supporting the roof.

The type of roof in question has several major advantages over built-uproofs and over metal-panel roofs using fasteners to secure the panels toone another and- /or to the roof supporting structure. The greatestadvantage is the water-tightness of the roof structure which is achievedby the reduction or the elimination of fasteners to secure the panelstogether and/or to secure the panels to the roof. The absence offasteners not only increases the water-tightness of the roof structurebut sharply reduces roof installation costs. The water-tight featurepermits a substantially flatter roof with consequent savings ininstallation costs and in the costs of internal heating and cooling.Additionally, the cliptype structure provides for better expansion orcontraction characteristics.

The invention contemplates substantial improvements in the panels andimprovements in the clip construction for standing-seam roofs of thekind mentioned. The structure of the invention maximized the advantagesmentioned above.

One object of the invention is to provide V-shaped sections on ahold-down clip and on abutting panel sidewalls which closely interfitwith one another and establish large bearing surfaces which function topositively secure the panels down on the roof supporting structure.

Another object of the invention is to provide interlitting V-shapedsections on a clip and panel edges functioning for panel hold-downpurposes and in addition serving as a track to support or guide aseaming carriage.

Another object of the invention is to provide interfitting track andhold-down V-sections on the hold-down clips and on the abutting panelsidewalls together with ribs or contoured feet at the bottom of the seamwhich function to resist panel spread and thereby maintain theV-sections in firm engagement.

Another object of the invention is to provide interfitting panelsidewall structure which offers high resistance to seam rupture andthereby permitting a singlefold seam which provides savings in materialand reduces installation costs.

Another object of the invention is to provide interfitting panelsidewall structure having a single-fold seam which permits the seamparts to be partially formed upon manufacture and thereby reducesinstallation labor costs and requires a less powerful, hence lessexpensive seaming machine.

Another object of the invention is to provide panel structure havingsidewalls which, when adjacent panels are laid down on the roof, form astarting seam having a partially crimped top portion which issubsequently finished crimped by a machine running along the seam.

Other objects and advantages of the invention will be apparent from thedescription below taken in conjunction with the followiing drawingswherein:

FIG. I is a perspective view ofa building having a panel-type roofconstructed in accordance with the invention;

FIG. 2 is a perspective view of a pair of panels of the invention set upside-by-side;

FIG. 3 is a sectional elevational view showing the shape of thehold-down clip and the shape of the topside and underside walls of theadjacent panels, the clip and walls are shown in a position prior tobeing interfitted together;

FIG. 4 is a perspective view of the hold-down clip and the topside andunderside walls of FIG. 3;

FIG. 5 is a sectional elevational view taken on the lines 5-5 of FIG. 1illustrating how the panels are secured at the ridge;

FIG. 6 is a fragmentary sectional elevational view taken on the lines6-6 in FIG. 5, except that for purposes of clarity the clip and top ofthe sidewalls are shown in the unseamed condition and the cross-sectionof the clip is shown in a heavy black line;

FIG. 6a is an enlarged view of the top part of FIG. 6 after crimping;

FIG. 7 is a fragmentary sectional elevational view taken along the lines77 in FIG. 5 illustrating the panel sidewalls as locked together by theseaming operation, for purposes of clarity the parts are shown as beingspaced apart;

FIG. 8 is a sectional elevational view taken on the lines 88 of FIG. 1illustrating how the panels are secured at the cave;

FIG. 9 is a sectional elevational view taken on the lines 9-9 in FIG. 1illustrating how the panels are secured at the rake;

FIG. 10 is an exploded view illustrating the construction of anover-lapping joint.

In FIG. 1, the pre-engineered metal building B has a roof 1 constructedin accordance with the invention. The panel-type side and end walls 2and 3 and the internal framing are conventional. The framing may includethe columns 4, girts 5, girders 6, end-wall rafters 7 and purlins 10.The purlins 10 support the various panels P making up the roof. Thepanels P extend from the ridge 1] to the eave 12. The standing seams areindicated by the dark lines. Certain other parts of the internal framinghave been omitted for the sake of clarity. For further details on theside walls and framing for the type of building described, reference maybe had to assignees publication SPECIFICATION DATA PDF 372.

The panels P used in roof 1 are identical in crosssection and are set upside-by-side and have upstanding walls which are fitted together to formthe seam. The shape of the panels is shown as FIG. 2, where the panels13 and 14 are disposed side-by-side in position prior to being fittedtogether. Each panel includes a central web 15, topside wall 16 andunderside wall 17 which respectively extend outwardly from oppositeedges ofthe central web. The central web has strengthening ribs 20 whichextend the full length of the panel. In preferred dimension, the web isapproximately 24 inches wide and the walls 16 and 17 are approximately2% inches in height.

The central web is adapted to be supported by the purlins 10 as thepanel extends from ridge to eave. The various panels are disposedside-by-side on the roof with the topside wall and the underside wall ofadjacent panels being locked together to form a standing seam. Hold-downclips are concealed in the seam between the side walls 16 and 17. Theclips are fastened down on the purlins.

The manner in which the panels are held down on the purlins by thehold-down clips and the manner in which the side walls are interfittedand locked to form the seam are important features of the invention. Thestructure of the clip and the side walls will next be described.

ln FIGS. 3 and 4 the roof clip 21 has a lower section 22 and a tabsection 23 which is moveably connected to the lower section. The lowersection includes the flat base 24, leg 25 extending at right angles tothe leg, 21 lower bearing flange 26 connected to the top of the leg andextending from the leg at an obtuse angle 27 of approximately 135", topbearing flange 28 connected to the lower bearing flange 26 and extendingoutwardly over the flange 26 at an acute angle 29 of approximately 70.An upwardly extending strengthening flange 30 is connected to thebearing flange 28. Prefer ably, the flange 30 is a co-planar with theleg 25.

The flanges 26 and 28 form a Vshaped section 31 which is adapted tointerfit with similar V-shaped sections on the walls 16 and 17 as willbe noted later.

The base 24 is adapted to be mounted directly on a purlin preferably bya self-drilling fastener extending through the base aperture 32.

The tab 23 is moveably connected to the lower section 22 as by the loopsection 34 extending through the slot 35 in the bearing flange 28. Asnoted, the tab ex tends upwardly adjacent to and above the strengtheningflange 30 and terminates in a bent over holding flange 36. Preferablythe strengthening flange 30 has a slot aligned with the tab 23. The slotallows some freedom of movement of the tab and reduces bulging in theseaming operation as will be noted later.

The topside wall 16 has a topside rib 41 and topside leg 42 which isconnected to and extends upwardly from the rib. Generally centrally ofthe wall is the topside lower V-flange 43 which is connected to the topof the leg 42 and extends outwardly at an oblique angle 44 ofapproximately 135. Connected to the flange 43 is the topside upperV-flange 45 which extends over the flange 43 at an acute angle 46 ofapproximately 70. The flanges 43 and 45 form a V-section 47. As mountedon the purlins, the V-section 47 is in juxtaposition with respect to theV-section 31 on the clip so that the two sections will interfit andengage.

Connected to flange 45 is the topside sealing flange 50 comprised of ariser section 51 and a crimping section 52. Preferably the riser 51 isco-planar with the leg 42.

The underside wall 17 includes the underside rib 54, the underside leg55, the underside lower V-flange 56, underside upper V-flange 60, theunderside sealing flange 61 which includes the riser section 62 andcrimping section 63. The lower V-flange 56 extends at an oblique angleof 135 with respect to the leg 55 and the upper V-flange extends at anacute angle of 70 with respect to the lower V-flange 56. The flanges 56and 60 form the V-section 64 which, when the panel is mounted on theroof purlins. is in interfltting position with the V-section 31 on theclip.

The various components making up the clip and sidewalls as mentionedabove are dimensioned so that the same will engage and interfittogether. Since the clips are spotted on the purlins. this nesting takesplace in the purlin area. The general condition of the seam S at apurlin is shown in FIGS. 6 and 6a. In the span between the purlins,there is no clip and the sidewalls directly nest or interfit togetherand this general condition is shown in FIG. 7.

The oblique angle of 135 and the acute angle of are important inattaining maximum holddown effect by the bearing flanges of the clip andby V-flanges of the sidewalls, yet permitting easy assembly of thetopside wall to the underside wall.

While we will go into detail later on as to how the panels are put downon the roof, for purposes of describing the above referred to interfit,we will touch on installation technique briefly. Refer to FIGS. 3, 4, 6and 6a.

Assume that the right hand edge of panel 14 (FIGS. 3 and 4) is lockeddown on the roof. The clip 21 is butted firm against the underside wall17. The clip foregoing is done by hooking the tab 23 over the sealingflange 61 and rotating or pushing the clip down until the V-sections 31and 64 and legs 25 and 55 engage. The base 24 is then pushed down firmon the purlin and locked by a self-drilling fastener. This anchors theunderside wall 17 down on the purlin.

The topside wall 16 of the panel 13 is then butted up against theanchored underside wall 17 and clip 21. The foregoing is accomplished byhooking the sealing flange 50 over the sealing flange 61 and the tab 36and then rotating the panel down until the \/-sections 47 and 31 andlegs 42, 25 and 55 engage and the panel is firm on the purlins.

1n the top or crimping portion 69 of the seam (FIG. 6), the flanges 52,36 and 63 at the purlin area (or the flanges 52 and 63 between thepurlins) by extending angularly outwardly as shown are in partiallycrimped condition. The seam is in ready condition for a final crimpingoperation. This is done by a crimping machine later in the installationprocess and the result is to bend the flanges 52, 36 and 63 at thepurlin area down into the position shown in FIG. 6a and bend flange 52and 63 as shown in FIG. 7. In FIG. 6, topside riser section 51 is firmagainst the clip strengthening flange 30 (with the tab 23 movingsomewhat into the slot 40) and the underside riser section 62 is alsofirm against the strengthening flange 30. The underside crimping section63 extends down and is firm against the riser 62. The tab holding flange36 is firm against the crimping section 63. The topside crimping section52 is down firm against the underside crimping section 63. The legs 42and 55 of the topside and underside walls are in the firm engagementwith the leg 25 of the clip. The V-section 31 of the clip is nested withthe V- sections 47 and 64 of the side walls.

The topside sealing flange 50 by fitting over and enveloping the tab andthe underside sealing flange and by that the parts are forced togetherby the crimping operation a seal is formed along the top of the seam.

A preferred type of crimping machine or roofers carriage is shown in US.Pat. No. 3,773,005 assigned to the assignee of this invention. Withreference to that patent, it will be noted that the interfitting Vsections 47 and 64 serve as guides or tracks for the machine.

Preferably the topside sealing flange 50 is provided with a strip ofcaulking material 65 so that when the topside sealing flange 50 is putover the tab 23 (and the sealing flange 61), the caulking materialspreads out to form a sealing barrier. For purposes of clarity, we havenot shown the caulking material in FIGS. 6, 6a, and 7.

The manner in which the clip operates to hold down the panels will nextbe explained. By virtue of the nesting of the V-sections 31, 47 and 64,the bearing flange 26 of the clip engages the underside lower \-flange56 while the other bearing flange 28 of the clip engages the topsideupper V-flange 45. Any lifting or upward motion of the right hand panel14 will be resisted by the bearing flange 26. Any lifting or upwardmotion of the left hand panel 13 will be resisted by the bearing flange28. Thus the V-sections of the clip being nested within the V-sectionsof the sidewalls function to lock or anchor the panels down in aposition on the roof. Since there is a clip at each purlin, the holdingforce is substantial.

The ribs 41 and 54 on the walls 16 and 17 are primarily for the purposeof maintaining the V-sections 47 and 64 of the walls engaged with theV-section 31 of the clip. The ribs 41 and 54 provide substantialresistance to spreading or separation of the walls 16 and 17.

Without ribs, substantial spreading could occur under certain loadconditions and one or other of the wall flanges 45 and 56 could becomedisengaged with the hold-down bearing flanges 26 and 28 of the clip andtherefore allow one or both of the panels to lift out of position.

FIG. 7 represents the condition in the span between the purlins. Whilewe have shown the panels of the topside and underside walls as beingspaced apart, this has been done only for clarity of illustration. Thetopside riser 51 is firm against the underside riser 62. The undersidecrimping section 63 is bent back firm against the underside riser 62.The topside crimping section 52 is bent down and firm against theunderside crimping section 63. Thus the sealing flange 50 envelops theunderside sealing flange 61 and forcing the parts together forms a seal.The legs 42 and 55 of the side walls are in substantial engagement. Thetopside lower V-flange 43 engages the underside lower V-flange 56 andthe underside upper V-flange 60 engages the topside upper V-flange 45.The ribs 41 and 54 continue to function to resist spreading of the walls16 and 17. Thus in the span areas, engagement of the V-flanges and theresistances of the ribs augment the holding power of the clips.

As will be apparent, the function performed by the Vsections and thefunction performed by the ribs extends throughout the length of thepanel and maintains the integrity of the whole standing seam.

The preferred manner of attaching the panels to the roof supportingstructure will next be described.

First, the starting and finish panels are formed. These panels are madeby slitting regular panels such as the panels 13 and 14. A starting andfinishing panel may be made by slitting one of the regular panels andusing the portion having the underside wall as a starting panel and theportion having the topside wall as the finish panel. In the embodimentshown herein a starting panel is formed by slitting along the lines 66of panel 14 and using the portion with the underside wall 17. The finishpanel is made by slitting along the dotted lines 67 in panel 13 andusing the portion having the topside wall 16.

A support angle 67 is mounted on the purlins and extends from eave toridge. The starting panel 70 is disposed on the purlins and on thesupport angle and is located transversely at the rake 71 (FIG. 9) andalso at the ridge 11 (FIG. 5). Normally. the location of the edge of thepanel at the ridge will be a fixed distance from the ridge purlin. Aline is stretched across the ridge so that as the panels are installedthey will all be in line and set at the desired fixed distance. Afterthe starting panel is located, it is locked down by the self drillingfasteners 72 inserted at each of the purlins and between purlins on 12centers into the support angle. Normally. the starting panel is alsotemporarily fastened at the ridge area so as to prevent spreading orbulging.

The hold-down clips are then installed in each purlin except at theridge purlin and at the eave strut. The clips are put into place in themanner previously described. Then the next adjacent panel 73 (FIG. 9) isinstalled by putting its topside wall 16 over the underside wall 17 ofpanel 70. The clips are then spotted and fastened down to anchor theleft hand or underside wall of panel 73. After installing 7 or 8 panels,the same are then crimped with the machine mentioned heretofore. Theprocess is then repeated until reaching the finishing panel. Thefinishing panel will be installed by first interfitting its topside wallwith adjacent underside wall and then locking down its outside edgesimilarly as was done with the fasteners 72.

In installing the panels, it is preferred that at both the ridge and atthe eave ends, two beads of caulking be run down on the topside wall.The beads will then engage the underside wall and seal against the entryof water at the ridge and eave ends of the seam.

After all of the panels have been installed and seamed, the temporaryfasteners at the ridge are removed. The ridge channel 74 (FIG. 5) isprovided with an L-shaped sealing material 75. The panels are thenlifted slightly and the channel and sealing material are slid under theedge of the panels making sure the panel edges bite into the material74. Then the panels are locked down by the fasteners 76 spaced along theridge at approximately 4 inches centers.

The panel on the other side of the building are then installed in thesame manner. Then the ridge, the eave and the rake trim are put intoplace as described below.

Referring to FIG. 5, the ridge cover 77 is mounted on the respectiveridge channels 74 and 78 and are held down by the fasteners 80 spacedalong the ridge at approximately l2 inches centers. Referring to FIG. 9,the rake trim 81 is secured by the fasteners 82 and 83. Incidentally, atthe ridge, the rake trim on each side of the roofing extends underneaththe ridge cover 77 and is locked in position by a fastener.

Referring to FIG. 8, the cave flashing 84 is supported by the eave strut85. The flashing extends along the length of the eave. The panels andflashing are locked down on the eave strut by the fasteners 86 whichextend along the eave at approximately 8 inches centers. The eave trim87 is held in place by the fasteners 90 and 91.

In cases where the length of the roof from the ridge to the eaverequires more than one length of panel, the same are overlapped at apurlin and are preferably held down by fasteners rather than by a clip.Also. the crimping sections on the sidewalls are notched whereby tominimize the layers of metal that must be crimped.

With reference to FIG. 10, the panels 93 and 94 represent the lower rowof panels which extend from the eave say to the center of the roof. Thepanels 95 and 96 represent the upper row of panels which extend from thecenter to the ridge. The row of upper panels is adapted to overlap thelower row, the overlap area being indicated at 97 and extending in orderof approx imately 8 inches.

In the overlap type of construction the panels are put down similarly asin the non-overlap arrangement. To begin the installation, a startingpanel such as panel 93 is put down to extend from the cave to the middleof the roof. Then the next panel 94 is put down to overlap at 95 andextend up to the ridge. The hold-down clips are installed except at theoverlap area. Following this the panel 96 and then the panel 97 are putdown, etc.

To avoid excess layers of metal at the overlapped area, the undersidewalls are notched. Thus in panels 93 and 94, the underside crimpingsections 100 and 101 are respectively notched at 102 and 103. When thetopside crimping sections 104 and 105 of the panels 96 and 97 are fittedover the crimping sections 100 and 101 there will be only a double layerof metal in the notched area.

The absence of additional layers at the notched area is importantbecause it avoids the development of internal stresses which mightotherwise cause fracture and lead to leakage especially with contractionand expansion of the roof due to temperature changes. Additionally, theabsence of additional layers of metal does not put undue strains on thecarriage during the seaming operation.

It will be understood that in some locations a layer of insulation isused on the roof and ordinarily this will comprise batts which aredraped over the purlins. In the event insulation is used, it is put downjust prior to the installation of a panel.

We claim:

1. A standing seam connecting an adjacent pair of panels together, theseam being formed by interfitting topside and underside walls on therespective panels,

the first panel including an underside wall having:

a. an underside rib to be disposed adjacent to the support structure forthe roof;

b. an underside leg connected to and extending upwardly from theunderside rib;

c. an underside lower V-flange connected to the underside leg andextending outwardly at an oblique angle thereto;

d. an underside upper V-flange connected to the underside lower V-fiangeand extending outwardly and over the underside lower V-flange at anacute angle thereto;

. an underside sealing flange having a riser section connected to theunderside upper V-flange and extending upwardly therefrom and alsohaving a crimping section connected to the riser section and extendingoutwardly at an acute angle thereto;

second panel including a topside wall having:

a topside rib to be disposed adjacent to the supporting structure forthe roof;

b. a topside leg connected to and extending upwardly from the rib andgenerally parallel to and substantially engaged with the underside leg;

c. a topside lower V-flange connected to the topside leg and extendingoutwardly at an oblique angle thereto and being substantially engagedwith the underside lower V-flange;

the

d. a topside upper V-fiange connected to the topside lower V-flange andextending outwardly and over the topside lower V-flange and at an acuteangle thereto and being substantially engaged with the underside upperV-flange;

a topside sealing flange having a riser section connected to the topsideupper V-flange and extending upwardly therefrom and being in substantialengagement with the underside riser section and also having a crimpingsection bent back on and in substantial firm engagement with theunderside crimping section, the riser section and crimping section ofthe topside sealing flange forming a cover over the underside sealingflange and thereby sealing the seam against entry of water.

2. A construction in accordance with claim 1 further including caulkingbetween the topside and underside sealing sections.

3. A construction in accordance with claim 1 wherein the topside andunderside ribs are mirror images.

4. A construction in accordance with claim 1 wherein each said obtuseangle is approximately I35 and each said acute angle is approximately 5.A standing seam connecting a pair of adjacent roof panels together incombination with a hold-down clip concealed in the seam for holding thepanels on the roof supporting sturcture, the seam being formed byinterfitting topside and underside walls on the respective panelsenveloping the clip by that:

the first panel including means for mounting the panel on roofsupporting structure and also including a topside wall having a V-shapedsection;

the second panel including means for mounting the panel on the roofsupporting structure and also including an underside wall having aV-shaped section; holddown clip disposed between the topside andunderside walls and having a lower section including a base mounting theclip on the roof supporting structure and V-shaped section above thebase interfitting with the V-section on the topside wall and alsointerfitting with V-section on the underside wall, the V-sections of theclip bearing on V- sections of the respective walls for holding therespective panels down on the roof supporting structure; and

a sealing flange on said topside wall, the sealing flange extending overand being firmly crimped against the top of said underside wall wherebyto seal the seam against entry of water.

6. A construction in accordance with claim 5 further including caulkingbetween said sealing flange and the top of said underside wall.

7. A roof panel comprising:

a central web;

an underside wall and a topside wall respectively extending outwardlyfrom opposite edges of the central web;

the underside wall including;

a. an underside rib connected to the central web;

b. an underside leg connected to and extending upwardly from theunderside rib;

c. an underside lower V-flange connected to the underside leg andextending at an oblique angle thereto;

d. an underside upper V-flange connected to the underside lower V-flangeand extending over the lower V-flange and at an acute angle thereto;

e. an underside sealing flange having a riser section connected to theunderside upper V-flange and extending upwardly therefrom and alsohaving a crimping section connected to the riser section and extendingoutwardly at an acute angle thereto;

the topside wall including:

a. a topside rib connected to the central web;

b. a topside leg connected to and extending upwardly from the topsiderib and generally parallel to the underside leg;

c. a topside lower V-flange connected to the topside leg and extendingat an oblique angle thereto, the oblique angle being substantially thesame as first said oblique angle;

d. a topside upper V-flange conneced to the topside lower V-flange andextending over the topside lower V-flange and at an acute angle thereto,the acute angle being substantially the same as first said acute angle.

e. a topside sealing flange having a riser section connected to thetopside upper V-flange and extending upwardly therefrom andsubstantially parallel to said underside riser section and also having acrimping section connected to the topside riser section and extendingoutwardly at an acute angle thereto, the acute angle being substantiallythe same as first said acute angle.

8. A construction in accordance with claim 7 wherein each said obliqueangle is approximately 135 and each said acute angle is approximately 9.A construction in accordance with claim 7 wherein said central web isprovided with a plurality of ribs.

10. A construction in accordance with claim 7 wherein said undersidelower and upper V-flanges form a V-shaped section which points inboardof the central web and wherein said topside lower and upper V- flangesform a V-shaped section which points outboard of the central web.

1. A standing seam connecting an adjacent pair of panels together, theseam being formed by interfitting topside and underside walls on therespective panels, the first panel including an underside wall having:a. an underside rib to be disposed adjacent to the support structure forthe roof; b. an underside leg connected to and extending upwardly fromthe underside rib; c. an undErside lower V-flange connected to theunderside leg and extending outwardly at an oblique angle thereto; d. anunderside upper V-flange connected to the underside lower V-flange andextending outwardly and over the underside lower V-flange at an acuteangle thereto; e. an underside sealing flange having a riser sectionconnected to the underside upper V-flange and extending upwardlytherefrom and also having a crimping section connected to the risersection and extending outwardly at an acute angle thereto; the secondpanel including a topside wall having: a. a topside rib to be disposedadjacent to the supporting structure for the roof; b. a topside legconnected to and extending upwardly from the rib and generally parallelto and substantially engaged with the underside leg; c. a topside lowerV-flange connected to the topside leg and extending outwardly at anoblique angle thereto and being substantially engaged with the undersidelower V-flange; d. a topside upper V-flange connected to the topsidelower Vflange and extending outwardly and over the topside lower Vflangeand at an acute angle thereto and being substantially engaged with theunderside upper V-flange; e. a topside sealing flange having a risersection connected to the topside upper V-flange and extending upwardlytherefrom and being in substantial engagement with the underside risersection and also having a crimping section bent back on and insubstantial firm engagement with the underside crimping section, theriser section and crimping section of the topside sealing flange forminga cover over the underside sealing flange and thereby sealing the seamagainst entry of water.
 2. A construction in accordance with claim 1further including caulking between the topside and underside sealingsections.
 3. A construction in accordance with claim 1 wherein thetopside and underside ribs are mirror images.
 4. A construction inaccordance with claim 1 wherein each said obtuse angle is approximately135* and each said acute angle is approximately 70*.
 5. A standing seamconnecting a pair of adjacent roof panels together in combination with ahold-down clip concealed in the seam for holding the panels on the roofsupporting sturcture, the seam being formed by interfitting topside andunderside walls on the respective panels enveloping the clip by that:the first panel including means for mounting the panel on roofsupporting structure and also including a topside wall having a V-shapedsection; the second panel including means for mounting the panel on theroof supporting structure and also including an underside wall having aV-shaped section; a hold-down clip disposed between the topside andunderside walls and having a lower section including a base mounting theclip on the roof supporting structure and V-shaped section above thebase interfitting with the V-section on the topside wall and alsointerfitting with V-section on the underside wall, the V-sections of theclip bearing on V-sections of the respective walls for holding therespective panels down on the roof supporting structure; and a sealingflange on said topside wall, the sealing flange extending over and beingfirmly crimped against the top of said underside wall whereby to sealthe seam against entry of water.
 6. A construction in accordance withclaim 5 further including caulking between said sealing flange and thetop of said underside wall.
 7. A roof panel comprising: a central web;an underside wall and a topside wall respectively extending outwardlyfrom opposite edges of the central web; the underside wall including; a.an underside rib connected to the central web; b. an underside legconnected to and extending upwardly from the underside rib; c. anunderside lower V-flange connected to the underside leg and extending atan oblique angle thereto; d. an undersidE upper V-flange connected tothe underside lower V-flange and extending over the lower V-flange andat an acute angle thereto; e. an underside sealing flange having a risersection connected to the underside upper V-flange and extending upwardlytherefrom and also having a crimping section connected to the risersection and extending outwardly at an acute angle thereto; the topsidewall including: a. a topside rib connected to the central web; b. atopside leg connected to and extending upwardly from the topside rib andgenerally parallel to the underside leg; c. a topside lower V-flangeconnected to the topside leg and extending at an oblique angle thereto,the oblique angle being substantially the same as first said obliqueangle; d. a topside upper V-flange conneced to the topside lowerV-flange and extending over the topside lower V-flange and at an acuteangle thereto, the acute angle being substantially the same as firstsaid acute angle. e. a topside sealing flange having a riser sectionconnected to the topside upper V-flange and extending upwardly therefromand substantially parallel to said underside riser section and alsohaving a crimping section connected to the topside riser section andextending outwardly at an acute angle thereto, the acute angle beingsubstantially the same as first said acute angle.
 8. A construction inaccordance with claim 7 wherein each said oblique angle is approximately135* and each said acute angle is approximately 70*.
 9. A constructionin accordance with claim 7 wherein said central web is provided with aplurality of ribs.
 10. A construction in accordance with claim 7 whereinsaid underside lower and upper V-flanges form a V-shaped section whichpoints inboard of the central web and wherein said topside lower andupper V-flanges form a V-shaped section which points outboard of thecentral web.